Definition
Introduced after the 2002 Tricolor collisions, this mark has equal vertical blue and yellow stripes, a standing or upright yellow cross topmark, and an alternating blue and yellow light with a one second flash and half second eclipse, written Al Bu Y 3s. It is deployed as soon as practicable after a new danger appears and is normally removed once the wreck has been surveyed, promulgated by Notice to Mariners and marked conventionally.
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